Natural cheese is generally made by adding a microorganism to milk that is capable of metabolizing lactose to produce lactic acid. The milk is usually set by using a coagulating agent or by developing acidity to the isoelectric point of the protein. The coagulating agent may include a curding enzyme, an acid, a suitable bacterial culture, or a composition thereof. The coagulum or curd that results generally incorporates the protein casein (which has been suitably altered by the curding process), fats (including natural butter fat) and flavorings arising during processing (especially when using a bacterial culture as the coagulating agent). The set milk is then cut to separate the resulting curd from the whey. The curd may be pressed to provide a cheese block in which curing generally takes place over a period of time under controlled conditions.
After the curd is separated from whey (e.g., using a centrifugal separator such as in U.S. Pat. No. 2,387,276), stabilizers, salt, and other ingredients may be added. Finally, the product is packaged and chilled. Many variations to this process have been introduced throughout the years (see, e.g., U.S. Pat. No. 5,656,320; U.S. Pat. No. 5,079,024; U.S. Pat. No. 5,180,604; U.S. Pat. No. 6,419,975; U.S. Pat. No. 6,406,736; U.S. Pat. No. 6,558,716; U.S. Pat. No. 6,416,797; and U.S. Pat. No. 4,597,971).
Cream cheese is a particularly soft, mild, acid-coagulated uncured cheese made from a mixture of cream and milk. Cream cheese has a smooth and butter-like body and is stored under refrigeration conditions. The texture and cream cheese body at refrigeration temperatures is such that the cream cheese can be sliced and spread. In traditional manufacturing of cream cheese, uncultured whole milk and/or skim milk and sweet cream are blended in pre-selected proportions to form a cream cheese mix. The cream cheese mix normally has a butterfat content of from about 10 to about 20 percent. After processing, the finished cream cheese has a butterfat content of from about 33 to about 35 percent by weight. The cream cheese mix is pasteurized and homogenized, after which it is cooled, usually to a temperature between 62 and 92° F., and is then inoculated with a lactic acid culture. The mix is held at the inoculation temperature until it has ripened and formed a coagulum. The coagulation process may, optionally, be aided by the addition of a small amount of rennet. The acidity of the coagulum is from about 0.6 to about 0.9 percent (calculated as percent equivalent lactic acid). After the desired acidity is obtained, the curd is separated from the whey and packaged.
At one time, casein was considered an essential protein component for making cheese products, including cream cheese. In fact, the functionality of casein and caseinates, such as sodium caseinate, have made casein one of the most widely used protein sources in a number of foods, such as cheese, cheese products, and whipped toppings. As a result, caseinates traditionally have been relatively expensive, leading to increased focus on protein alternatives. For instance, the use of vegetable proteins, such as soy protein, has become increasingly popular in making inexpensive cheese analogues.
Whereas casein and caseinates are in high demand and high in cost, whey proteins are relatively low-cost, and are often even discarded as a byproduct of the cheese making process. This underutilization of whey protein has led to increased focus on methods of manufacturing cheese products using concentrated whey protein or whey protein isolates. For instance, U.S. Pat. No. 6,419,975 discloses a method for making caseinless cream cheese-like products that use non-casein proteins such as whey protein. In addition to the aforementioned advantages of incorporating whey protein into food products, this process also has an advantage in that it does not require a coagulation or fermentation step, since the process begins with whey protein rather than the formation of a curd from milk. Therefore, the process may be carried out in a much shorter time frame. Other prior art patents also focus on the use of other non-casein proteins, such as soy or other vegetable protein, for making cheese-like products.
An additional benefit of incorporating significant amounts of whey proteins into food products is that they have high nutritive value for humans. In fact, the amino acid composition of whey proteins is close to an ideal composition profile for human nutrition. Whey proteins are also understood to have superior emulsifying capabilities in comparison with casein. Without wishing to be bound by theory, the incorporation of whey protein is expected to reduce defects such as phase separation during processing. In addition, such whey proteins provide a low cost dairy product which, if successfully incorporated into cheese products, would significantly increase the overall efficiency and effectiveness of the cheese making process.
Conventional experience has indicated that reducing the level of casein in cream cheese formulations makes it much more difficult to achieve and maintain a desirable finished texture of the food product, such as in terms of firmness, smoothness, spreadability, etc. Therefore, it would be desirable to provide a continuous process for making cream cheese products, particularly high moisture low fat content cream cheese products using low casein or casein-free cream cheese formulations and mixes, that still achieves and maintains acceptable texture and other sensory attributes.
Under the current Standards of Identity, cream cheese is required to contain at least 33 percent fat and no more than 55 percent moisture. Lower fat cream cheeses usually contain correspondingly higher proportions of moisture due to the decreased fat content. For instance, USDA specifications for light and reduced fat cream cheese allow for up to 70 percent moisture. However, increased moisture levels in the cream cheese will often result in a cream cheese product that is too soft and does not have the desired firmness of normal, higher fat cream cheese. Therefore, gums traditionally have been added to low fat cream cheese in order to impart a firmer texture. Unfortunately, the addition of gums and the like also results in a more gel-like texture that is less desirable than the smooth, creamy texture of normal cream cheese, and does not spread as well as normal cream cheese. Therefore, there remains a need for a low fat, high moisture cream cheese or cream cheese-like product that has a firm and spreadable texture similar to normal cream cheese and has increased yield stress and decreased deformation (decreased gel-like texture) when compared to conventional low fat, high moisture cream cheese. There also remains a need for a low fat, high moisture, low casein cream cheese or cream cheese like product that has a firm and spreadable texture similar to normal cream cheese and has increased yield stress and decreased deformation when compared to conventional low fat, high moisture, low casein cream cheese. It is also desirable to provide a continuous process using non-casein protein (i.e., alternative protein) to make a cheese-like product with texture and firmness like that of normal cream cheese. It is also desirable to provide a low-fat cream cheese with lower casein content and higher whey protein content that has texture and spread attributes similar or identical to traditional, higher fat cream cheese. The present invention provides such a high moisture cream cheese having the desired texture and spread attributes, as well as other advantages further described herein.
A number of prior art patents have attempted to create low fat cheeses with substantial amounts of whey protein. For instance, U.S. Pat. No. 5,356,639 to Jameson discloses a process for the production of a fermented concentrate from various milk products (e.g., whole milk, skim milk, or milk with added milk components). The process includes the steps of (1) selectively concentrating milk; (2) increasing the ionic strength of the concentrate to maintain the milk in the liquid phase and therefore prevent formation of a coagulum both during and after fermentation; (3) fermenting the concentrate with lactic acid producing bacteria; and (4) removing water from the fermented liquid concentrate. The final product includes substantially all of the whey proteins originally present in the milk. However, Jameson still has a casein-to-whey ratio of approximately 80:20, and requires a greater length of time to obtain a finished cheese-like product due to the necessity of a fermentation step.
Guinee et al. (Int. Dairy Journal 5:543-568 (1995)) reviewed the general state of the art relating to incorporation of whey protein into cheese or cheese products. High-heat treatment of milk impairs rennet coagulation, curd syneresis, curd structure and texture, as well as functional properties such as meltability and stretchability of the resulting cheese. The heat treatment of milk, after being curded to form semi-hard cheeses, does allow production of cheeses having higher whey protein levels. Unfortunately, such cheeses also exhibit poorer curd fusion and lower yield stress (fracture) values during ripening. Such cheeses also have higher moisture content, often resulting in a gel-like texture and, without the benefit of the present invention such cheeses do not have the desirable texture of normal cream cheese.
U.S. Pat. No. 6,558,716 to Kent describes methods for increasing the whey protein of cheese by providing a “functionally enhanced” whey protein. The method requires combining a cheese curd and whey protein composition to form a whey protein-cheese curd blend, and then subjecting the whey protein-cheese curd blend to high shear and an elevated temperature for a time sufficient to provide a stable cheese product supplemented with whey protein. The heat treatment effectively transforms the whey protein to produce a “functionally enhanced” whey protein which allows for the formation of a stable cheese product containing the functionally enhanced whey protein. Preferably, the blend is homogenized at a pressure of about 1,000 to about 8,000 psi and treated at a temperature from about 175 to about 215 degrees Fahrenheit. Kent discloses a method of incorporating whey protein in cheese products, but does not teach a method for replacing casein outright with whey protein. Kent also requires a fermentation step to produce a stable cheese having significant levels of whey protein.
U.S. Pat. No. 6,419,975 and U.S. Pat. No. 6,406,736 to Han describe methods of creating a casein-free cheese. According to the process of the invention, non-casein protein is mixed with hot water and melted fat to form an emulsion. The emulsion is then subjected to a homogenization step and a heating step. The pH of the resulting compound is then adjusted to about 4 to about 6, and then subjected to a second homogenization step to form a cream cheese product.
U.S. Pat. No. 6,303,160 to Laye attempts to solve the problems with texture in the prior art by providing a high moisture cream cheese with increased firmness by maintaining moisture levels during the manufacturing process at levels below the final target moisture level of the final cream cheese product; the moisture level of the final composition is then adjusted to the final target moisture level by the addition of water. Manipulating the moisture content of cream cheese in this manner has been shown to result in increased levels of firmness in the final cream cheese product. This process, however, requires a fermentation step, and therefore a lengthy production time.
Canadian Pat. No. 2,442,387 to Wolfschoon describes a method of incorporating whey proteins into foodstuffs to provide a casein-to-protein ratio of up to 20:80 by acidifying an aqueous solution of one or more whey proteins, blending with a fat to create an acidified whey protein fatty emulsion, and blending the emulsion with a foodstuff. A cream cheese product with the desired yield stress and deformation of the present invention is not described.
U.S. Pub. No. US 2004/0219273 A1 to Cha discloses the use of acid whey (pH 3.5-5.5, preferably 4.6-5.2) to make cream cheese-like products. Gums may be added to increase the yield stress of such compounds. However, Cha does not disclose starting with a whey compound with sufficient acidity to obtain the desired firmness and texture of the present invention. Cha also fails to disclose a low fat cream cheese-like product with moisture levels as high as in the present invention while still maintaining the desired firmness and texture. The steps and conditions of the present invention are specifically designed to use highly acidic pH treatments, heat treatments, and homogenization to significantly increase the yield stress and decrease deformation of high moisture low fat cream cheese products beyond what is disclosed in prior art processes.
U.S. Patent No. 6,261,624 to Hudson describes hydrolyzing a whey protein preparation in acid and heating to form a weak gel that is dried and ground into powder that may be used as a thickening agent in foodstuffs. Hudson does not describe manufacture of a high moisture low fat cream cheese with enhanced firmness and texture properties